This application in general relates to tube cutting apparatus in which each major component may be easily replaced relative to the others. Further, improvements to the components are also disclosed.
Modern tube cutting apparatus typically include a number of separate components. First, a track bed supports a die set which typically includes a clamp and cutting blade. A drive or accelerator accelerates the die set on the bed up to the speed of a tube to be cut. A ram is forced downwardly onto the die set by a ram drive to actuate the clamp and cutting blade to cut the tube during movement of the die set. Thus, the basic components could be said to include a bed, a die set, an accelerator, a ram and a ram drive. The ram and ram drive may be collectively referred to as a powerhead. Apparatus for cutting other materials may not need each of the above components. As one example, some materials may not have needed a clamp. However, they still would require the other components.
In the prior art, these components, other than the accelerator, have all typically been permanently incorporated into a single unit. Thus, a user who wishes to change a die set to cut a larger size of tubing, has typically not been able to utilize the same bed, ram, or accelerator. The mounting for the components have typically all been welded together such that they cannot be replaced as individual units. Thus, that user has typically been required to purchase additional tube cutting apparatus for differing application.
The prior art accelerators for moving the die set had some deficiencies. It would be preferable that a simple rotating drive be utilized to accelerate the die set along its path on the bed. It has been difficult to achieve such a drive that is not undesirably large in both mass and physical size, however, and such units have not been practically developed. Further, to conserve space it would be preferred that the accelerator be positioned along the path of the die set.
The prior art powerheads also have deficiencies. In one prior art powerhead, a pair of eccentric shafts are driven to selectively drive the ram into the die set. These systems were deficient in that the mounting for the bearings of the first and second shafts were not readily accessible. Further, gear teeth on the eccentric shaft underwent large cyclic stresses, such that the large stresses were borne by certain teeth, which were prone to failure. Finally, in theory, the two shafts are always synchronized such that the ram remains parallel to the bed. In practice, due to gear tooth and bearing clearances, there is often slippage, or relative misalignment between the two shafts, such that parallelism between the shafts is lost. This is undesirable. Ideally, exact parallelism must be maintained.